The present invention relates to a microcapsule type adhesive to be applied to a threaded surface of a threaded member such as screw, bolt, nut, or the like, to prevent loosening or impart a close-contact property (both hereinafter referred to as "prevent loosening") thereto.
Heretofore, as a loosening preventing adhesive to be applied to a threaded surface (screw thread) of a threaded member such as screw, bolt, nut, or the like, there has been known a composition comprising a microcapsule containing a reactive adhesive and a resin as a binder, using an organic solvent or water as a solvent, for example in Japanese Patent Publication Nos. 11051/1970 and 46339/1977 and Japanese Patent Laid Open Nos. 308876/1990 and 11883/1978.
However, such known microcapsule type adhesives involve drawbacks poor adhesion, poor storage stability and likelihood of causing an environmental pollution. For example, if there is used as a binder an emulsion, e.g. acryl emulsion, or a dispersion type binder, the emulsifying or dispersion stability is impaired by a curing agent used, resulting in increase of viscosity and difficulty of application in many cases. And in the case where polyvinyl alcohol or gelatin film is used as a wall film, it is difficult to prevent the deterioration of its performance due to swelling caused by water for example. Moreover, the use of an acrylic resin as a reactive adhesive causes deterioration not only in bonding strength at high temperatures but also in solvent resistance. Further, many conventional microcapsule type adhesives employ organic solvents, but the use of organic solvents not only causes the problem of environmental pollution but also may badly affect the worker's health during application to screw, bolt, nut, or the like.
It is the object of the present invention to solve the above-mentioned problems of the prior art.